Ok, here's my theory! I believe that Teach was a guy who did stuff for survival. The world is fluffed up so maybe his dad went craycray and was going around doing really bad stuff and Teach forgot as his dad may have been the one who hit him??? I dont know really but its so weird cause you dont know if he's remembering everything accurately. Also Guwon is totally an experiment gone wrong and probably the only person who sees what the world is actually like and how to "save it". Im sorry for the long rant but im so invested in the plotヾ(☆▽☆)
Loving these replies! Ok to the comments about why people don’t recognise him I’m thinking that they’re all so focused on Guwon as their master/leader/idol whatever that they’re not concerned about anyone else unless they see them within his vicinity cause since they’re all dogs to him he keeps them on a leash and out of reach but what happens when one dog starts being favoured over the others they of course notice and finally fixate on that one particular person which is where all this jealousy comes from! You know like in anime when there’s girl groups who idolise the popular male lead and are his “fan club” and beat the female lead cause their pack mentality is “he belongs to all of us not just one of us” that’s how I’m thinking but also might be a stretch. Either way loving any other thoughts!

Was teach a hound who escaped and somehow lost his memory and ended up living with his “dad” that’s why Guwon was there that day cause he was actually hunting him down to bring him back and that’s why at the start was so disgusted to be intimate with him cause he only saw him as a tool and was like “wtf why would I fuck with you” but now is aware of his feelings towards teach but that doesn’t change the reality of his crazy personality. Or ??? Please add your thoughts too I’m excited to read other people’s opinions